Maria Kushunina

Taxonomic significance of seed morphology in the genus Mollugo s.l. (Molluginaceae)

ABSTRACTThe genus Mollugo L. comprises ca. 35 species distributed throughout the tropics, and it is clearly polyphyletic. The seed morphology and ornamentation of 27 Mollugo representatives is studied with regard to their significance for systematics and taxon delimitation. The species belonging to the “M. cerviana” and “M. fragilis” groups, as well as M. tenella, are characterized by D-shaped or roundish seeds, whereas other taxa have reniform seeds. The seed ornamentation can be considered to be one of the most valuable characters for disentangling the taxonomic diversity in the genus. Mollugo cerviana shares the same reticulate ornamentation with M. namaquensis, M. pusilla, M. tenella and M. tenuissima, while the smooth surface is peculiar to M. fragilis, M. spathulata and M. walteri. The close relationship of M. fragilis and relatives to Hypertelis spergulacea is carpologically supported. Some taxa share a papillate ornamentation (M. decandra, M. floriana, M. molluginis, M. nudicaulis, M. pentaphylla,...

Chorological and taxonomic notes on African plants

Abstract The taxonomy of complicated native African taxa, Biscutella maritima (Brassicaceae) and annual species of Sesuvium (Aizoaceae) is discussed. The distribution of B. maritima is widened to the most of the coastal areas of NE Algeria and N Tunisia. Morphological differences with regard to other North African members of Biscutella ser. Biscutella are reported to facilitate the identification of B. maritima. We propose to accept four annual Sesuvium species (instead of the one previously accepted species, S. sesuvioides sensu amplissimo) with different distributions in Africa: S. digynum, S. hydaspicum, S. sesuvioides s.str. and S. nyasicum. A delimitation key based on morphological and carpological characters is provided. Lectotypes of S. digynum, S. digynum var. angustifolium, S. hydaspicum, S. nyasicum, Diplochonium sesuvioides (Sesuvium sesuvioides) and Trianthema polysperma (synonym of Sesuvium hydaspicum) are selected. Other discussed taxa belong to the alien elements of the flora. Atriplex semibaccata (Amaranthaceae-Chenopodiaceae) is reported as a new species for Cape Verde. Gaillardia × grandiflora (Asteraceae) is discovered as a new species for Africa found in Morocco. Prosopis velutina (Fabaceae) is collected for the first time in Northern Africa (Morocco). Mollugo verticillata (Molluginaceae) is recorded as a new species for DR Congo. Its morphology, including seed ornamentation, is discussed in reference to other similar-looking Molluginaceae. Incidence of American species Heterotheca subaxillaris (Asteraceae) in North Africa is discussed. Vernonanthura polyanthes (Asteraceae) is recorded as a naturalized invasive species in eastern Zimbabwe. It seems to be the first documented discovery of this ergasiophyte in Africa.

Contribution of apoplast to short-term copper uptake by wheat and mung bean roots

In this study we addressed the controversial issue of contribution of cell walls (CWs) to Cu binding in plant roots. We compared short-term Cu uptake at different solution Cu levels by mung bean (Vigna radiata (L.) R. Wilczek) and wheat (Triticum aestivum L., cv. Inna) and by root CWs isolated from either Cu-treated or non-treated plants. Twenty four hours of plant exposure to Cu affected Cu-binding capacity of mung bean root CWs but not wheat CWs. Amounts of Cu associated with CWs and roots increased with Cu concentration. The Cu accumulated in CWs could account for total Cu content of roots (except for wheat in highest Cu treatment). Pectin content of the CWs and their Cu-sorption capacity were positively correlated. The accumulation of Cu in root CWs is a principal response of wheat and mung bean plants to excess Cu, limiting symplastic Cu uptake in roots in short-term treatment. The contribution of CWs to Cu absorption by plant roots depends on Cu level in the medium and plant species.

Diagnostics, taxonomy, nomenclature and distribution of perennial Sesuvium (Aizoaceae) in Africa

Abstract The taxonomy of perennial Sesuvium species in Africa has been poorly investigated until now. Previously five perennial species of Sesuvium were recognised in Africa (S. congense, S. crithmoides, S. mesembryanthemoides, S. portulacastrum, and S. sesuvioides). Based on the differing number of stamens, S. ayresii is accepted here as being distinct from S. portulacastrum. Field observations in Angola also led the authors to conclude that S. crystallinum and S. mesembryanthemoides are conspecific with S. crithmoides. A new subspecies, Sesuvium portulacastrum subsp. persoonii, is described from West Africa (Cape Verde, Gambia, Guinea-Bissau, Mauritania, Senegal). The molecular phylogeny indicates the position of S. portulacastrum subsp. persoonii within the “American lineage” as a part of the Sesuvium portulacastrum complex which needs further studies. A diagnostic key and taxonomic notes are provided for the six perennial species of Sesuvium found in Africa and recognised by the authors (S. ayresii, S. congense, S. crithmoides, S. portulacastrum subsp. portulacastrum, S. portulacastrum subsp. persoonii, S. verrucosum and the facultatively short-lived S. sesuvioides). The distribution of S. crithmoides, previously considered to be endemic to Angola, is now confirmed for the seashores of Republic of Congo and DR Congo. The American species S. verrucosum is reported for the first time for Africa (the Macaronesian islands: Cape Verde and the Canaries). It is locally naturalised in Gran Canaria, being a potentially invasive species. These findings as well as new records of S. verrucosum from Asia and the Pacific Islands confirm its proneness to transcontinental introduction. Lectotypes of S. brevifolium, S. crithmoides, S. crystallinum and S. mesembryanthemoides are selected. The seed micromorphology and anatomy of the perennial African species is studied. Compared to the seeds of some annual African Sesuvium investigated earlier, those of perennial species are smooth or slightly alveolate. The aril is one-layered and parenchymatous in all species and usually tightly covers the seed. The aril detachments from the seed coat that form a white stripe near the cotyledon area easily distinguish S. verrucosum from other species under study.